In developing countries, 2.6 billion people remain without access to any kind of sanitation and 850 million remain undernourished. Thus, there is a critical need to develop sustainable technologies that provide sanitation while simultaneously recovering valuable nutrients and resources from the waste. Biofuels have not found widespread application so far because of higher cost and the significant stress they exert upon the agricultural commodities.
Biocatalysis of organic waste into useful chemical feedstock is a promising approach for managing waste and providing a renewable energy supply such as diesel. However, many current methods for producing renewable energy sources suffer from low yields and/or production from food commodities resulting in competition for crop resources.
Most lipids for commercial biodiesel production today are derived from food and agricultural commodities, e.g. soybean, jatropha oil, etc., inadvertently contributing to the rising food prices. Therefore, it is preferred to produce non-edible sources of lipids, in particular, lipids derived from oleaginous microorganisms such as yeast and other fungi, which have the capability to assimilate inexpensive organic carbon sources produced from existing technologies such as anaerobic fermentation and digestion and store them as lipids.
Anaerobic digestion has been practiced for centuries, but is still plagued by limitations to adequate mixing in the anaerobic bioreactors. Additionally, using bioreactor designs and operating configurations developed to date, it is only possible to either maximize methane production or volatile fatty acids. This results in high operating and capital costs for a given methane or acid output.
Organic material from waste water, sewage, and industrial waste can be reused to produce biogas using anaerobic digestion. Biogas, such as methane and volatile fatty acids, can be used for energy and as building blocks for chemical production, respectively. In anaerobic digestion, the organic material, or feedstock, is dissolved in water and mixed with methane and acid producing bacteria. However, current anaerobic digestion bioreactors suffer from lower yields of biogas production due to limited mixing between the feedstock and bacteria. In addition, the design of these bioreactors also allows for maximizing the yields of either methane or volatile fatty acids only, but not both.